It's a dangerous world. And even five years after 9/11, the nation remains far from ready to respond in an effective way to a major disaster such as a terror attack or a flu pandemic, says Irwin Redlener, director of the National Center for Disaster Preparedness at Columbia University's Mailman School of Public Health.

In his new book, Americans at Risk (Knopf, $24), Redlener urges the federal government to develop a cohesive, coordinated approach to disaster planning — and Americans to emerge from a state of national denial.

The warnings about potential "megadisasters" are being heard by Americans, Redlener writes, but "we don't quite know what we're supposed to do. ... Mostly we hope against hope that calamity isn't around the corner."

Getting past a state of fear or denial is the first step toward readiness that can be a key to survival in a disaster, Redlener says.

"I hear from a lot of people that 'if there's a really big disaster, there's nothing I can do about it.' " he says. "That's hardly ever true."

Only four in 10 Americans say they have a family emergency plan, though fewer than a third of those say they have all the needed elements in place. For many, the cost of accumulating the extra food, water and supplies recommended by the Department of Health and Human Services and the Federal Emergency Management Agency is prohibitive. And then there's the problem of storage space. "In urban areas, where are they supposed to store those supplies?" Redlener asks. "In New York City apartments, they literally don't have the room."

Yet, he says, "the details are not as important as the process. If you sit with your family and go through what you'd do in various scenarios, then when the unexpected happens your mind-set will be better prepared to deal with contingencies."

Having thought about it ahead of time and made whatever preparations are possible — such as learning CPR, knowing the evacuation plan for your community, deciding a family meeting place or discussing who will pick up the children from school — will give you a head start, Redlener says, even if the reality of the situation is not what was planned for.

"Mental resiliency and the capacity to think on your feet is a skill that can be developed by talking through what you can think of, and reading about it," he says. "The more you've practiced thinking about how you'd respond in unusual circumstances, the better you'll respond when the unexpected circumstance arises."

In his book, Redlener focuses less on what individuals can do to prepare than on what government should do. He poses five scenarios: an avian flu outbreak in New York City, an earthquake in Seattle, a nuclear attack in a major city, a train wreck in Missouri that causes the release of toxic chemicals, and a terrorist attack targeting elementary schools in Arizona. He also describes a nine-point strategy, starting with reconvening the 9/11 Commission to address preparedness efforts, and including expanding the role of the military in planning for and responding to major disasters.

"As I was working out the approach for this book," Redlener says, "I wanted to be clear on this point: Getting the country prepared is not a matter of government actions alone, nor is it something individual citizens can do alone. This is a partnership of government, the public, not-for-profit organizations and businesses, each one fulfilling its responsibilities.

"It has to be a dynamic partnership that allows the whole system to respond effectively."

"If you sit with your family and go through what you'd do in various scenarios, then when the unexpected happens your mind-set will be better prepared to deal with contingencies," says Irwin Redlener, director of the National Center for Disaster Preparedness at Columbia University's Mailman School of Public Health.